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<title>5.9.1 Mutex Objects </title>
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<h2><a name="SECTION007910000000000000000"></a><a name="mutex-objects"></a>
<br>
5.9.1 Mutex Objects 
</h2>

<p>
<tt class="class">mutex</tt> objects have following methods:

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-799' xml:id='l2h-799' class="method">test</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Check whether the mutex is locked.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-800' xml:id='l2h-800' class="method">testandset</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
``Atomic'' test-and-set, grab the lock if it is not set,
and return <code>True</code>, otherwise, return <code>False</code>.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-801' xml:id='l2h-801' class="method">lock</tt></b>(</nobr></td>
  <td><var>function, argument</var>)</td></tr></table></dt>
<dd>
Execute <code><var>function</var>(<var>argument</var>)</code>, unless the mutex is locked.
In the case it is locked, place the function and argument on the queue.
See <tt class="method">unlock</tt> for explanation of when
<code><var>function</var>(<var>argument</var>)</code> is executed in that case.
</dl>

<p>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-802' xml:id='l2h-802' class="method">unlock</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Unlock the mutex if queue is empty, otherwise execute the first element
in the queue.
</dl>

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<span class="release-info">Release 2.5.1, documentation updated on 18th April, 2007.</span>
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